Cobalt-catalyzed mono-coupling of R 3 SiCH 2 MgCl with 1,2-dihalogenoethylene: a general route to γ-substituted ( E )-allylsilanes

Kamachi, Taku; Kuno, Akiko; Matsuno, Chikashi; Okamoto, Sentaro

doi:10.1016/j.tetlet.2004.04.098

Cited by 31 publications

(6 citation statements)

References 11 publications

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“…Experiments. Scheme displays the experiments that have been performed to determine the diastereoselectivities in crotylation reactions of aldehydes 16a − c , aldehyde dimethylacetals 20a − b as well as ketones 16e − f in dichloromethane as solvent for T = 195 K and 273 K. The two crotylation agents E - and Z -crotyl trimethylsilane ( E - 9 and Z - 9 ) have been synthesized according to methods reported in the literature , in excellent diastereoselectivities (≥99:1, determined by GC analysis). For MCC reactions, trimethylsilyl methyl ether ( 18 ) was added as silyl ether component.…”

Section: Resultsmentioning

confidence: 99%

Origin of Syn/Anti Diastereoselectivity in Aldehyde and Ketone Crotylation Reactions: A Combined Theoretical and Experimental Study

2006

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We report on experimentally determined and computationally predicted diastereoselectivities of (a) multicomponent crotylation (MCC) reactions of simple aliphatic aldehydes and ketones and (b) of acetal substitution (AS) reactions of aldehyde dimethyl acetals with E- and Z-configurated crotyl trimethylsilane to give homoallylic methyl ethers bearing two newly formed stereogenic centers. We found that corresponding MCC and AS reactions give nearly equal syn/anti ratios. While the crotylations of acetaldehyde and propionaldehyde mainly result in the syn product for E-configurated silane and in the anti product for Z-configurated silane, the syn product is found as main product for the crotylation of pivaldehyde regardless of substrate double bond geometry. Using butanone as substrate, the anti product is found as main product in both cases. By computational investigation employing the B3LYP/6-31+G(d) level of theory in dichloromethane solution (PCM/UAKS), we found that the attack of O-methyl-substituted carboxenium ions by crotyl silane explains the experimentally observed selectivities, indicating that these crotylations in fact proceed in an S(N)1-type reaction via this ionic intermediate. Comparison of relevant open transition-state structures leads to a rationalization of the observed selectivities. For all systems studied, three transition-state conformations are necessary and sufficient to determine the selectivity. This has been confirmed by studying the MCC reactions of isobutyraldehyde. Activation energies for the stereogenic step have been determined by calculation of the transition state and substrate structures in dichloromethane solution at the B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d) level of theory in dichloromethane solution. The possibility to predict simple diastereoselectivity in general Lewis acid-mediated crotylations of aldehydes and ketones is discussed.

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Section: Resultsmentioning

confidence: 99%

Origin of Syn/Anti Diastereoselectivity in Aldehyde and Ketone Crotylation Reactions: A Combined Theoretical and Experimental Study

2006

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“…Okamoto and co-workers, on the other hand, synthesized allylsilanes 16 by coupling (trimethylsilyl)methylmagnesium chloride (15) with 1,2-dihaloethene (E)-8a or 8b in the presence of a cobalt or nickel catalyst (Scheme 4). 6 Note that variation of the reaction conditions can promote formation of either the monocoupling or dicoupling product. They then transformed 16 into a variety of γ-substituted (E)-allylsilanes 17 and 19 via Kumada or Suzuki coupling.…”

Section: Alkylalkenesmentioning

confidence: 99%

1,2-Dihaloalkenes in Metal-Catalyzed Reactions

et al. 2018

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1,2-Dihaloalkenes readily undergo simultaneous or sequential difunctionalization through transition-metal-catalyzed reactions, which makes them attractive building blocks for complex unsaturated motifs. This review summarizes recent applications of such transformations in C–C and C–heteroatom bond forming processes. The facile synthesis of stereodefined alkene derivatives, as well as aromatic and heteroatomic compounds, from 1,2-dihaloalkenes is thus outlined.1 Introduction2 Synthesis of 1,2-Dihaloalkenes3 C–C Bond Forming Reactions4 C–Heteroatom Bond Forming Reactions5 Conclusion

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“…In a mixture of THF/NMP and in the presence of Co(acac) 3 (3 mol%), the cross-coupling of primary or secondary alkyl Grignard reagents with nonactivated alkenyl halides, including chlorides such as 256, takes place stereospecifically and in high yields [168] (Scheme 5.63). In the case of 1,2-dihaloethylenes, monoalkylation providing (E)-alkenyl halides is first observed [169], thus allowing for stepwise twofold alkylations. Alkenylation of silylmethylmagnesium halides represents a notable application of these couplings, as it provides a rapid stereocontrolled access to diversely substituted allylsilanes of synthetic value.…”

Section: Cross-coupling With C(sp 2 )-Electrophilesmentioning

confidence: 99%

Carbon–Carbon‐Bond‐Forming Reactions Mediated by Organomagnesium Reagents

Chemla

Ferreira

Pérez‐Luna

et al. 2013

Metal‐Catalyzed Cross‐Coupling Reactions and More

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IntroductionFirst reported at the beginning of the twentieth century [1], organomagnesiums are very important synthetic tools. In the field of coupling reactions, first examples of transition-metal-mediated reactions have been reported by Gilman and Lichtenwalter [2] with the oxidative homo-coupling of aryl Grignard reagents in the presence of transition metal halides as both catalyst precursors and oxidants. This reaction was later greatly improved by Kharasch [3], who showed that an efficient homo-coupling reaction could be observed with a small amount of CoCl 2 (3 mol%) and an organic halide as a stoichiometric oxidant. This breakthrough was then followed by the report in 1941 on cross-coupling reactions of arylmagnesium bromides with vinylic halides in the presence of various transition metal salts by the same group [4]. Surprisingly, this seminal work remained mainly unexploited, until this reaction was reinvestigated by several groups in the beginning of the 1970s [5]. Thus, Kochi and Tamura [6, 7] described in 1971 the use of Fe(III) salts as catalyst precursors for cross-coupling reactions, while Kumada [8] and Corriu [9] reported the use of nickel for similar transformations [10,11]. At the same time, the group of Normant [12] described the Cu-catalyzed reaction of the Grignard reagents with organic halides, followed by the report of Murahashi [13] on the use of palladium as a catalyst in similar cross-couplings. Most cross-coupling reactions have been performed with unfunctionalized Grignard reagents because no general method for preparing oligofunctional organomagnesium reagents was available. However, the situation is rapidly evolving, thanks to the groundbreaking work of Knochel and coworkers [14] on the preparation of highly functionalized Grignard reagents. In this chapter, the scope and limitations of cross-coupling reactions involving organomagnesium reagents are showcased with select examples from the recent literature with a special focus on functional-group-tolerant procedures. The recent developments of the most challenging transformations including either the use of oligofunctional metallic species or β-hydrogen-containing nucleophiles will be specially highlighted.

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Cobalt-catalyzed mono-coupling of R 3 SiCH 2 MgCl with 1,2-dihalogenoethylene: a general route to γ-substituted ( E )-allylsilanes

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Cited by 31 publications

References 11 publications

Origin of Syn/Anti Diastereoselectivity in Aldehyde and Ketone Crotylation Reactions: A Combined Theoretical and Experimental Study

Origin of Syn/Anti Diastereoselectivity in Aldehyde and Ketone Crotylation Reactions: A Combined Theoretical and Experimental Study

1,2-Dihaloalkenes in Metal-Catalyzed Reactions

Carbon–Carbon‐Bond‐Forming Reactions Mediated by Organomagnesium Reagents

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